Fix bugs and make improvements

- Get clone() working on FreeBSD
- Increase some Python build quotas
- Add more atomic builtins to chibicc
- Fix ASAN poisoning of alloca() memory
- Make MODE= mandatory link path tinier
- Improve the examples folder a little bit
- Start working on some more resource limits
- Make the linenoise auto-complete UI as good as GNU readline
- Update compile.com, avoiding AVX codegen on non-AVX systems
- Make sure empty path to syscalls like opendir raises ENOENT
- Correctly polyfill ENOENT vs. ENOTDIR on the New Technology
- Port bestline's paredit features to //third_party/linenoise
- Remove workarounds for RHEL 5.0 bugs that were fixed in 5.1

third_party/chibicc/kw.h

@@ -110,6 +110,8 @@
 #define KW___SYNC_LOCK_RELEASE          126
 #define KW___BUILTIN_IA32_PMOVMSKB128   127
 #define KW___BUILTIN_IA32_MOVNTDQ       128
+#define KW___ATOMIC_FETCH_ADD           129
+#define KW___ATOMIC_SUB_FETCH           130
 
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_